Underground conduit for steam mains



D66. 1, 1931. c, RANDALL 1,834,549

UNDERGROUND CONDUIT FOR STEAM MAINS Filed June 15, 1928 2 Sheets-Sheet lDec. 1, 1931. RANDALL 1,834,549

UNDERGROUND CONDUIT FOR STEAM MAINS Filed June 15, 1928 2 Sheets-Sheet 2Patented Dec. 1, 1931 MER YN o. RANDALL, or PHILADELPHIA, PENNSYLVANIAUNDERGROUND CONDUI'I FOR I STEAM MAINS iic fioafiied June 13, 1928.Serial No. 285,191. I

The primary object vof the present inven tion is to prevent the entranceo'f moisture or water to the conduits of steam distribution systems.This is accomplished by pro viding a section of conduit having neitherhorizontal nor vertical joints within the secform temporarily employedin the construction. 7

Objects of the present invention are to efiect a material saving in thecost of construction; to increase the strength of the finishedstructure; to effect a saving in the cost of excavation; to dispensewith temporary form work such as was hitherto quite generally employedon both the interior and e t-eriorincluding the top or roof of theconcrete boX that provided tlie conduit; to effect a material ,saving'oftime'and labor in the construction of the conduit; and to reduce thereinforcing rods used.

Other objects of the invention Will appear from the followingdescription.

The invention may be said to comprise an underground conduit for steammains including a corrugated sheet metal arch construction arranged overthe steam main, and concrete surrounding and encasing the outside of themetallic arch construction both providing a form and also constituting apermanent reinforcement for the concrete mass surrounding the archconstruction.

The invention also comprises the method of making an underground conduitfor steam mains which consists in digging a trench eX- cavation, placingroller supports and pouring a bottom slab of concrete, in said trench,grooving the edges of the slab by embedding a form therein andpermitting; the form to swell and loosen, when the slab is set removingthe form and placing the pipe or main on the roller supports, arrangingthe feet of sections of corrugated sheet metal arch construction in saidgrooves and assembling said corrugated sections, and surrounding andencasing the assembled arch construction with concrete.

The invention also comprises the improvements to be presently describedand finally claimed.

In the following description reference will be made to the accompanyingdrawings forming part hereof and in which F igure" 1 is a transversesectional view of an underground conduit for steam mains embodyingfeatures of the invention.

Fig. 2 is a transverse sectional view of, a

tion' of the conduit.

Fig. 3 is a side view of arch construction with parts broken away andparts in section, and i t F ig. 4 is atop or plan view of the form shownin Fig. 1. a

Referring to the drawings 1 is a corrugated sheet metal archconstruction arranged over the steam main 2 with space between. 3 and 4indicate concrete surrounding and encasing the outside of the archconstruction. The metal arch construction provides a form for theconcrete before it has set and it also constitutes a permanentreinforcement for a the concrete mass which surrounds it and fills thetrench or excavation 5 sufficiently. Thearch construction may befabricated in sections inthe shop from corrugated galvanized ironsheets, built up, as shown, of

three sectio11s,one rolled or curved section 6 forming the top, and twostraight sections 7 riveted to the tangents of'the curved secti'on. Asshown in Fig. 3 the rivet holes 8 are elongated to accommodateexpansion.

In the field the ends of the corrugated plates which make upthe archconstruction are fitted one within .the other as shown at 9 in'Iiig.-3.This also providesforexpansion due to "heat thrown off or given-out fromthe steammain 2 which is usually of the high pressure variety. The metalrods 10 in the concrete are provided to effect an equalizationoftemperature- 11 are roller supports for rollers 12 upon whichridesaddles 13 mounted under the pipe or, main 2 and secured thereto,asshown, by tie-rods 15. 16 indicates insulating material applied to theeX- terior of the pipe or main. f 7 By way of description it may be saidthat assuming that the arch construction isfabricated from corrugatedsheets of 18 gauge, the conduit will, carry a superimposed load of"approximately three hundred pounds without the concrete casing. Withthe concrete casing, about five or six inches thick, the superimposedload strength is approximately fifteen hunderd pounds per square foot orone hundred pounds per square foot greater than the customaryrequirements for a conduit placed in the street and subjected to heavytraflic loads.

According to the present invention an underground conduit for steammains is constructed as follows: v v v A trench 5 is excavated and sinceit need not exceed in width thewidth of the concrete, because notemporary forms are em ployed, the trench is comparatively ineX- pensiveto excavate. The rollersupports 11 are placed and the bottom slab 4 ofconcrete is poured. The edges of the slab 4 are grooved as at 17 byembedding into the slab the cleats 18, Fig. 2, of the ladderlike form 19Fig. 4. The form is permitted to swell and loosen and is then removed.

It will be'observed that the cleats 18 are bevel-ed inward at theirouter edges and are straight at their inner edges which facilitatestheir loosening in the concrete and at the same time there is providedin the face of the slab 4 a groove 17 having avertical edge 20 whichsupports the foot of the arch construction against inward pressure whenthe concrete 3 is poured. When the slab 4 is set the form 19 is removed.The pipe or main is placed on the rollers 12 and is properly insulated.The sections of the corrugated arch construction are assembled as thework progrosses and the feet of the arch construction are arranged inthe grooves 17. The surrounding and encasing concrete 3 is poured intothe trench and onto the arch constructionand onto the faces of the slab4 which project beyond the arch construction. 7 In this mass of concrete3 are arranged the rods 10 which, as already stated, serve the functionof equalizing the temperature. Obviously the work of construction mayproceed progressively and rapidly and it is inexpensive, re quireslittle labor and is both strong and durable.

' In the case of smaller conduits, such as service branches tobuildings,the conduit sections may be made from a single sheet instead of fromthree pieces.

It will be obvious to those skilled in the art to which theinventionrelates that modifications may be made in detailsofconstruction and arrangement and matters of mere form withoutdeparting from the spirit of the invention which is not limited to suchmatters or otherwise than the prior art and the appended claims mayrequire.

v 1. Asection of jointless, underground conduit for the insulated steampipes of a steam distributing system comprising a metallic archconstituting a form and reenforcement but spaced therefrom to provide anair space between said pipe and said arch, and a monolithicself-supporting layer of concrete circumferentially surrounding saidpipe and said 'arch so as to be reenforced by said arch.

3. Means for distributing steam comprising, a pipe, aninsulating'covering on said pipe, a sheet metal arch adjacent said pipebut spaced therefrom to provide an air space between said pipe and saidarch,'and a monolithic self-supporting layer of concretecircumferentially surrounding said pipe and said arch so as to bereenforced by said arch, the ends of said arch being embedded in saidconcrete.

4. An underground conduit for a steam main comprising a sheet metal archconstrue tion arranged over the steam main and concrete completelysurrounding said metal arch construction and said steam main, said metalarch construction both providing a form and also constituting apermanent reenforcement for the concrete surrounding the archconstruction;

MERWYN C. RANDALL.

